1. Technical Field
This invention relates to systems and methods for determining the relative location of items with respect to one another. More particularly, it relates to methods and apparatus for detecting and reporting the relative location of an indicating unit traveling along the length of an elongate detector. In a preferred embodiment, this invention senses the position of a magnetic indicating unit relative to an elongate detector thereby determining and reporting the location of one or more fluid interfaces within a multi-phase fluid reservoir.
2. Background Art
Many instances arise in both industrial and residential settings wherein the location of a reference point is desired to be detected and reported for evaluation. Many alternative methods may be employed for such purposes; an example is a video camera that either transmits or records a visual image of items that an operator desires to monitor. One drawback of such a system is that an operator is required to observe the image, make an evaluation, and then report that information for further processing if so required. With the advent of computers used as controllers for various processes, it is desirable to have automatic reporting systems that indicate relative locations of different components in a system. In a residential setting, an example would be a garage door that opens and closes by traversing tracks. In the event that the operation of such a door were to be automated, it would be necessary for the controller to know the relative position of the door with respect to the tracks thereby indicating its open or closed configuration, or its relative position somewhere in between. Such detection and reporting may be achieved by placing an elongate stationary detector along the track of the garage door and installing an indicating unit upon the traveling door in a position that travels adjacent to the length of the detector. By detecting and reporting the location of the indicating unit, a controller for the system can ascertain the door""s position and take action based thereon.
A linear relative location detecting and reporting system of the present invention finds a myriad of applications in industrial settings. In manufacturing processes, there are many instances in which human operators or automated controllers must know real time relative positions of certain parts in an apparatus. One particularly applicable situation is found in automated manufacturing processes wherein assembly lines are employed. By being able to detect the relative position of a conveyor within the manufacturing process, the degree of advancement or completion of a given task is detectable and reportable for control and evaluation purposes.
One particular industrial application and environment in which such a detection system has been found to be desirable is in liquid reservoirs wherein the position of fluid interfaces are desired to be detected. By detecting the interfaces between phases of fluids, the level, and normally the volume of one or more fluids present in a reservoir or container may be calculated.
In some circumstances, the interface will be between two fluids, each in a different state. The lower fluid will normally be in a liquid state and the upper fluid will typically be in a gaseous state. These conditions are common to most fluid filled tanks. Examples of such situations include containers for gasoline, water, crude oil, and liquid chemicals that are often retained in holding tanks. In each case, the lower phase of a fluid interface is liquid and the upper phase is usually air that fills the remainder of a partially filled tank. A detector may be similarly utilized in less contained environments such as in subterranean reservoirs and in flood plane areas to measure water level conditions.
There are several known devices that are employed in liquid reservoirs for detecting interfaces, and in turn liquid levels of both single and multi-phase liquids. Two such examples have been previously invented and patented by a common inventor of the present invention in U.S. Pat. Nos. 4,976,146 and 5,347,864 for Liquid Level Measuring Apparatuses issued to Senghaas. Each of those systems, however, employ different apparatus and methods of operation than is presently being disclosed. In each, a plurality of reed switches are installed upon an elongate support or back board in an angled configuration with respect to the length of that board. The apparatus of the two Senghaas Patents ""146 and ""864 each employ reed switches arranged in a vertical series, but each switch is significantly angled with respect to horizontal.
The reed switches operate in response to magnetic forces applied thereto. When no magnetic force or same pole magnetic forces are applied to each of two leads of the switch, the reed portions are biased away from one another thereby keeping the switch open and preventing current from being transmittable thereacross. Oppositely, when magnetic forces of opposite or north and south poles are applied to the leads of the reed switch, the two reeds of the switch are attracted to one another thereby closing the switch and accommodating the transmission of applied current thereacross. The overlapped configuration of adjacent switches accommodates a cancellation affect that is utilized for achieving an error correcting procedure, but which is no longer required in the present invention.
Each of the ""146 and ""864 inventions employ one or more toroidal magnets that surround the series of angled vertical switches and move relative thereto in an up and down direction. The use of such toroidal magnets slidably fitted about a series of detection switches have also been employed in such earlier examples as the Hall-Cell Liquid Level Detector disclosed in U.S. Pat. No. 4,361,835 issued Nov. 30, 1982 to Nagy. While reed switches were not employed in the ""835 patent, Hall-Cell sensors were alternatively used as detectors responsive to the influence of toroidal or donut-shaped magnets moved up and down the length of a series of such Hall-Cells.
The measuring devices of the earlier Senghaas patents, like the present invention, have a common physical constraint because of the environment in which they are most commonly utilized. That environment is installation in liquid containing tanks, and more specifically in large above ground holding tanks for crude oil, water and the like that have been constructed to accept liquid level measuring devices that are inserted through a pre-formed aperture in the top of the tank. Because of the high cost associated with modifying this aperture, it is important that new devices developed for employment in such applications and settings be constructed to satisfy the criteria and limitations of these tanks and the existing measuring device receiving apertures.
In some instances, the tops or covers of such tanks rise and fall together with the level of liquid contained therein. Therefore, sliding movement of the lid about the measuring device must be facilitated. To alter this preexisting configuration of the tanks would be exceedingly expensive and prohibitive to the employment of measuring devices that deviate from these constraints. Therefore, these apertures dictate the maximum diameter or width of measuring devices that may be inserted therein. As a result, the size of the aperture also governs the width of the support board upon which the reed switches are mounted in both the previously known measuring devices and that of the present invention.
Because of performance limitations of components employed in the earlier measuring apparatuses of the ""146 and ""864 patents, it was necessary that the reed switches be angularly positioned with respect to horizontal on their supporting back boards. Specifically, the actuating toroidal magnets heretofore available had a limited strength and therefore required a more substantial lead area, sometimes achieved through elongation of the reed switch leads, in order for the switch to be influenceable to a closed configuration by the magnet. To accommodate these relatively long lead lengths on each side of the reed switch necessary to be responsive to the relatively low magnetic force of the available toroidal magnets, the angled orientation was utilized to permit elongation of the individual switches and facilitate the xe2x80x9ccancellationxe2x80x9d effect of adjacent switches during operation. This orientation, however, compromises not only the manufacture of the apparatus, but also its utility by restricting conditions for transport, as well as affecting the switch""s sensitivity to the magnetic field produced from within the magnet-carrying float.
Because of the requirement that the reed switches be positioned upon the back board in an angular orientation, the installation of each individual switch must be made manually. This necessitates personnel being employed for a highly intricate and repetitive task. As a result, these assemblers are at risk of developing such conditions as carpal tunnel syndrome caused by the repetitive and tedious manual manipulation. Therefore, the possibility of injury to the worker has made it highly advantageous to facilitate an orientation wherein the installation of the reed switches may be automated. Such a condition is found in the present invention wherein, because of a new and inventive design, the reed switches are able to be oriented in a substantially horizontal configuration that is perpendicular to the length of the support board upon which the switches are mounted.
Not only were the toroidal magnets employed in the previous systems of relatively low magnetic strength, but the magnetic force developed by the toroidal magnets was not focused inwardly toward the switches. Instead, a magnetic field was developed about several switches which were influenced as a group by the toroidal magnet. Because of the inability to focus the effects of the toroidal magnet upon a single switch, it was necessary that the series of switches be overlapped with respect to adjacent switches to provide sufficiently fine position indications.
An example of such a previously known measuring apparatus is illustrated in FIGS. 4, 8 and 11 As may be seen in the widthwise cross-section of FIGS. 8 and 11 the previous reed switch was mounted above the back board on leads that extend upwardly and away from the back board and then inwardly toward the reed portions that are flexible between open and closed switch configurations. Because of the switch""s elevated configuration, damage is likely if the switch is pressed against in the direction of the board. This potential damage stems from the construction of the switch which includes a glass housing or sheath in which the reeds of the switch are intended to be protected for more reliable operation. Each lead portion that extends outside the housing is contiguous in most instances with an associated reed portion within the housing. An interface occurs where the elongate lead/reed member enters the glass housing. This interface can serve as a pivot point between the two portions on either side of the glass housing when downward pressure toward the board is experienced on the elevated housing. This can result in a distortion of the intended orientation of the interiorly located reed portions. In many instances, relatively soft metals are employed in the manufacture of the lead/reed members to potentiate responsiveness to a magnetic field, while at the same time resist becoming magnetized. One of the drawbacks, however, of these softer metals is that they are more susceptible to plastic deformation, as opposed to elastic deformation, and will not regain their original positions once deformed, such as when being depressed toward the back board. These changes in orientations are likely to adversely affect operation of the deformed switch.
The back board, as shown in FIG. 8, is relatively rigid in a widthwise direction. In contrast, the back board is substantially more flexible in a lengthwise direction as is illustrated in FIG. 11. If the back board is flexed as shown in FIG. 6, there is a likelihood that the reed switches mounted thereon will become misaligned to an extent that they fail to operate as designed. The back board may be sufficiently flexed during transport to distort the position of the reeds inside the glass body of the switch so that it never regains its original and operatable configuration and therefore fails to operate upon installation. As a result of this detrimental effect, systems manufactured according to these previous designs had to be transported under strict conditions to prevent the above described damage to the individual reed switches. This is a significant disadvantage in that it requires the measuring apparatuses to either be assembled on site or to be transported in a rigidified and elongate state. Each of these two options have proved burdensome.
If required to assemble the measuring apparatus on site, it is possible that the operation of the unit will be compromised because of inhospitable conditions experienced at many tank locations. Among others, there will likely be dirt and dust that can affect the system""s operation, as well as environmental conditions such as extreme heat that affects those personnel required for assembly. Similarly disadvantageous is assembling these systems in a factory setting and transporting them to a remote site in an elongate rigid state using trucks with long beds. Because most trucks are designed to carry articles of substantial weight when such a length is required, the employment of such trucks is exceedingly expensive in view of the apparatus"" relative light weight, but long length.
The microprocessor control of these prior systems require that the switches be assembled in a specific order and that that order be maintained because of the reporting processes for transmitting closed-switch information up the elongate detector to the microprocessor at the sensor""s top end. Because each switch is identified and mapped to the controller based on its position, it is required that the switches and the back boards to which they are attached be assembled in a prescribed order. It is also necessary that assembly be made by a trained technician to assure that all proper conductive connections are achieved in the assembled measuring apparatus. In that the number of switches employed upon a particular measuring apparatus dictates the number of communication paths and interconnections required to transmit detected data to the microprocessor, these paths and interconnections increase with sensor length. This imposes not only manufacturing and assembly constraints on the previous designs, but it also necessitates the employment of experienced and trained personnel for installation. In view of these known constraints, it has therefore become highly desirable to have a design that may be more compactly transported and assembled on site without the inherent deficiencies associated with the prior designs disclosed in the ""146 and ""864 patents.
In view of the above described deficiencies associated with the use of known detection sensors, the present invention has been developed to alleviate these drawbacks and provide further benefits to the user. These enhancements and benefits are described in greater detail hereinbelow with respect to several alternative embodiments of the present invention.
The present invention in its several disclosed embodiments alleviates the drawbacks described above with respect to conventional detection sensors and incorporates several additionally beneficial features. This invention includes features and/or components that have been invented and selected for their individual and combined benefits and superior performance as a relative location detecting and reporting system. The system includes multiple components that individually and singularly have new and novel features in and of themselves. Each of the individual components, however, work in association with each other to achieve many of the benefits derived from the system. Together, the components yield an overall relative location detection and reporting system that has superior effectiveness and performance over previously designed systems for accomplishing similar results.
The present invention is contemplated to be employable in many environments, including both residential and industrial, wherein its detecting and reporting features may be advantageously utilized. As described above, the present invention will be useful where it is desired to know the location of an item traveling along an elongate path both with respect to position and change in position with respect to time. Therefore, not only are time fixed quantities such as a liquid level height or an object""s distance from a starting position able to be determined and/or calculated through the use of the present invention, but such time relative quantities as speed and acceleration may also be ascertained.
While the embodiments illustrated herein show elongate detectors that are configured upon substantially straight line or linear configurations, it is also possible that the detector may be curvilinearly shaped thereby facilitating employment in manufacturing and other applications wherein the path upon which items are to be monitored is curvaceous and potentially three dimensional in travel course. An example is an assembly line""s path through a factory and the employment of the present invention""s elongate detection unit for monitoring an indicator that may be carried either upon the circulating mechanism or conveyor belt of the assembly or upon an item being carried upon the conveyor as illustrated in FIG. 3. In either case, useful information may be detected and processed for automated control of the manufacturing operation.
A preferred embodiment of the present invention is utilized for detecting fluid interfaces in a multi-phase fluid reservoir. It is contemplated that its employment may be in containers such as tanks or in uncontained environments both above ground and at subterranean levels. It is also contemplated that the present invention may find application in multi-phase fluid bodies wherein lower phases are in a liquid states and upper phases are in gaseous states. Still further, it is also contemplated that more than one interface may be detected by a single sensor. In preferred embodiments, these detections are accomplished by one or more floating indicators wherein each floating indicator carrier has a density that causes that indicator to ride substantially at the interface of two different fluid phases.
Because of the present invention""s novel structure and inclusion of newly available technologies and components heretofore unavailable, beneficial features are enjoyed with respect to manufacturing and production, transport, assembly, and operation of the relative location detection apparatus. A primary feature responsible for the present invention""s superior characteristics and performance is best appreciated in FIG. 7. Therein, a horizontal orientation of a plurality of reed switches is shown with respect to the support board upon which the reed switches are mounted. In a preferred embodiment, the support board is constructed from a printed computer circuit board upon which several reed switches are mountable and upon which electrical transmission lines are integrated and carried.
In an alternative embodiment, the configuration of the individual switches may not be fixed on a support board, but instead established by connection within an orienting flexible housing or sheath. This flexible combination may then be rigidified by a separate member into which the combination is installed for use. An example of such a rigidifying member would be a C-shaped angle constructed from substantially rigid material that would fix the several switches"" relative positions by their installation into the void of the interior of the C-shaped member.
The horizontal orientation of the switches provides many benefits and is made possible at least in part by the utilization of a specialized high intensity magnet previously unknown in such an application. The discovery of such an application of the high intensity magnet has greatly simplified manufacture of the detector by facilitating the superior horizontal configuration of the switches.
In a preferred embodiment, the high intensity magnet includes a unique material, neodymium, as a constituent component. This material is capable of taking a superiorly strong magnetic charge. Not only is the magnetic charge and resultant exertable force exceedingly strong, but it is also focusable so that its effects are more accurately directed and applied to an individual reed switch without affecting adjacent switches. The characteristics of the high intensity neodymium magnet in comparison to the previously described and employed toroidal magnets may be likened to a focused laser beam compared to the divergent light beam of conventional light sources.
The employment of such a high intensity magnet has facilitated the horizontal configuration of the reed switches. That is, reed switches having shorter leads may be employed because they are operationally responsive to the greater power of the high intensity magnets, where they would not have been responsive to the weaker toroidal magnets. By reducing the lead lengths of the switches, the horizontal orientation of the switch across the support board is possible. This is so even in view of the fact that the width of the support board remains dominated in most cases by outside constraints such as the dimensions of apertures through which the sensor must be insertable as described hereinabove. Because the focused magnetic force does not affect adjacently positioned switches, a close configuration of successive switches is made possible resulting in relatively fine resolution capabilities with respect to detectable indicator positions.
The horizontal and uniformly spaced orientation of the reed switches in their installation upon the support board facilitates automation of the installation process. Whereas manual fixation of each reed switch was previously required, all reed switches are now capable of being automatically positioned and mounted upon the support board. Because of this new horizontal orientation of the switches across the support board, the switches may be purchased in standard reel form and applied in an automated manner without direct manual manipulation required. The Zevatech Placemat 560 Laser is an example of an appropriate automated placement machine utilizable for this process. This has eliminated a tedious task for personnel and otherwise freed their time for more stimulating and productive tasks.
The horizontal orientation of the reed switches, as opposed to the previously angled orientation, prevents distortion of the reed switch from lengthwise flexing or bending of the support board. This feature enables two major beneficial characteristics of the present invention: the first being prevention of damage to the reed switch because there is no longer a twisting or torque effect experienced in the perpendicularly oriented switch and the second being the ability to facilitate and enhance the support board""s ability to bend in a lengthwise manner. The enhanced bending characteristic has been found to be highly beneficial because a coiled orientation of the elongate and assembled support board is now possible for transport purposes. Because there is an almost negligible risk of damage to the switches upon such coiling, the support board may be suitably constructed to allow at least the detection unit portion of the invention to be coiled as tightly as upon a three foot diameter. In this coiled configuration, the unit may be appropriately packaged and quite easily shipped to an installation site.
Because of the almost elimination of deformation to the switch in the present invention, the specific orientation of the switch upon the support board is no longer as critical as in previously known devices. As may be appreciated in FIGS. 8 and 11 flat reed and lead portions were primarily utilized in previously known devices. As a result, the glass encasing housings of the switches were generally rectangular in cross-sectional shape and helped assure that the switches were properly oriented on the back board when fixed thereto. By contrast, the present invention can utilize switches in which the lead and/or reed portions are flat and ribbon shaped or cylindrically shaped as may be appreciated in FIGS. 12 and 13. Still further, the reed portions may be located above and below one another or side-by-side when installed on the support board. Each of these features is facilitated by the fact that no deformation is imparted to the switch, even when the switch-carrying support board is wrapped into a coiled configuration as shown in FIG. 14.
As a further enhancement to the new design of the present invention, recesses have been provided in the support board for the reed switches as shown in FIGS. 9 and 12. In a preferred embodiment, an individual elongate recess is provided for each switch in the form of an aperture cut through the support board as shown in FIGS. 10 and 13. Each recess provides a receiving area within the support board for at least a bottom portion of a reed switch. In at least one configuration, the reed switch is constructed with a protective encasement around the flexible reed portions in the form of the glass housing previously described. The recess provides a void within which all or a portion of the switch may be inlaid. This provides a certain degree of protection for the recessed portion of the switch that is contained within the board, but it provides a more general protection of the entire switch by lowering the switch toward the board and causing it to project less distantly way from the board upon which it is carried thereby making the switch less susceptible to damage as a result of being pressed upon. By recessing the switch into the support board, it is possible to have the leads of the switch extend directly outward from ends of the switch and into engagement with a switch-side surface of the board and not form a right angle as previously required. This also reduces the torsional factors and bending forces applied to the switch during flexion of the board along its lengthwise axis. By reducing the distance between the longitudinal lengthwise axis of the switch and widthwise axis of the support board and moving them closer into coincidence with one another, deformation of the switch is reduced thereby facilitating not only the flexibility of the support board, but also the coiled transport configuration described hereinabove. Still further, by cutting away portions of the support board, either in the form of depressions in the board""s surface or apertures all the way therethrough, the mass of the board is reduced and it becomes more flexible, particularly with respect to its lengthwise axis. This increased flexibility facilitates the coiled configuration of the detection unit found so highly advantageous for transport purposes. These beneficial characteristics may be best appreciated in FIGS. 4 through 6.
It is expected that at least three embodiments of these sensor systems will be initially manufactured and sold, but others are likely to soon follow. A first of the three embodiments will comprise a fully assembled detection unit that is custom made with respect to length at the factory. This detection unit may then be pre-installed in a protective fiberglass tube as shown in FIG. 15 before shipping. The fiberglass pipe may be constructed from one long section, or created by appropriately connecting several pipe sections together in an end-to-end configuration to achieve the elongate pipe.
As a second alternative, the detection unit may be fabricated to a custom ordered length and then coiled for shipping as shown in FIG. 14. The protective fiberglass pipe may be shipped to the same site in easily transported sections that are connected into the required end-to-end configuration at the site. It is anticipated that the end-to-end connection of the pipe sections may be by any suitable means such as connected matable threads or epoxy glue.
As a third embodiment, it is contemplated that an elongate detection apparatus may be made up of a series of individual detection units that have been plugged together in an end-to-end configuration. Each individual detection unit may have different or similar lengths. By providing three standard lengths of three feet, four feet and five feet, any configuration length may be established in one foot increments greater than three feet. A longer section may also be made available for spanning greater distances with fewer connections.
As will be described in more detail hereinafter, a preferred embodiment of the controlling mechanisms for the present invention facilitate one hundred and twenty switches in a group. It is possible to include more than one group of switches on a given support board and therefore, in theory, boards of almost infinite length may be manufactured.
Each detection unit terminates at each of its two ends in either a plug or a plug receiver. These plugs accomplish not only a physical connection and optional locking of the detection units into an elongate detector, but they also provide the electrical conductivity across the entire length of the elongate detector required for communicating information up and down the system. Through this plugability, shipping is facilitated where relatively short single units are transported to a site before being assembled. It also reduces or eliminates the need for highly trained personnel to assemble the system at the remote site. Similarly, the sensor""s plugable construction makes it possible for the detection unit to be easily disassembled after a particular use and reassembled at another location without detriment to the reliability of the detecting and reporting system. This is a substantial benefit over other known sensors which are essentially single use devices because debilitating damage often occurs in the removal and reinstallation of the earlier and less forgiving sensors.
The control and reporting means of the present invention have also been newly developed and provide unique apparatus and methods for detecting and reporting measured conditions. Like other known measuring devices used in liquid reservoirs, the present invention not only detects fluid interfaces in contained fluids, but other conditions such as temperature may also be detected and reported. In the present invention, unlike previously known measuring apparatus, the order of assembly of the several detection units that make up the elongate detector is not critical. Instead, upon start-up of a reading sequence each detection unit is initialized and prescribed an address. This is accomplished by including several reporting and repeating modules that are generally associated with each detection unit: that is, a reporting and repeating module is provided for at least every one hundred and twenty reed switches. Each of those modules is controlled by and reports to a microprocessor interface capable of initiating the operation of each module and the apparatus with which it is associated, but the interface also receives information from the modules and may have capabilities for processing and evaluating that information and transmitting it to a remote location for still further processing.
In order to conserve power which may be limitedly available at the remote site of the system""s employment, the components of the apparatus go to a low or non-power consuming xe2x80x9csleepxe2x80x9d mode. The controlling interface will normally be programed to initiate a detection process on a regular time basis. For each detection process, an initialization signal is sent from the controller down the elongate detector in a relayed sequence through the consecutive reporting and repeating modules. Upon initialization, each module is awakened and its address specified with respect to its position in the descending order of modules. This is accomplished by sending a first signal to the top module which reads its address and then increments that address plus one and sends it to the next module. That second module receives its plus one address and adds another which is sent to the third module. This process is repeated down the module line until each has been awakened and specified an address. The last module is able to identify itself as such and returns a message which is repeated up through each and every module back to the controlling interface microprocessor signifying that the initialization procedure has been completed. The processor then may poll the detector string for information about closed switches or such other information as temperature readings.
The messages sent down through the detector may be global in nature. That is, no specific detection unit is addressed, instead, the message is characterized by the information it seeks. For instance, when seeking the position of the indicator magnet relative to the elongate detector, a polling message will be sent to the first module. That first module reads the messages and determines that it must detect whether or not one or more of its switches are presently closed by the influence of an adjacently positioned magnet. At the same time, the global message is passed down the line to module two which carries out the same procedure. If a positive response is detected in any one or more detection units, that information is relayed up the detector to the controlling microprocessor. The reading sequence will not conclude until the lower most module has reported indicating that each module in the string has been polled. Alternatively, now that each module is known to the interface, specifically addressed messages may be passed through the detector. In that case, each module receives the message and reviews the address to see if it matches its own. If it does not, it passes by repeating the message to the next module in the series for similar evaluation. When the module is reached that matches the address specified by the interface, a responsive routine is executed and the message is not passed further down the detector length. These initializing, addressing, and polling features that are passed through reporting and repeating modules are heretofore unknown characteristics in relative location detecting and reporting systems.
Referring now to specific embodiments of the linear relative location detecting and reporting system, additional benefits and advantageous features will be appreciated.
In one embodiment, a relative location detection apparatus including a detection unit having a support board having a plurality of spaced reed switches mounted along a lengthwise axis of the support board. Each of the reed switches has a longitudinal axis oriented substantially perpendicular to the lengthwise axis of the support board. A high intensity magnet is coupled to the support board for movement relative to the support board and in a direction substantially parallel to the support board""s lengthwise axis. The magnet has north and south poles that are oppositely positioned to one another and directed toward one another across a width of the support board and into periodic alignment with the longitudinal axes of the reed switches. The magnet has a magnetic force sufficiently focused so that the magnet actuates the reed switches individually thereby indicating the magnet""s location.
The magnetic actuation closes the reed switches and the magnetic force is sufficiently focused so that only one reed switch may be closed by the magnet at any one time. If so desired, however, two or three switches may be closed at one time to provide redundancy for increased reliability.
In at least one embodiment, a plurality of high intensity magnets are coupled to the support board for movement relative to the support board and in a direction substantially parallel to the support board""s lengthwise axis.
In a further embodiment, there is at least one recess in the support board configured for receiving at least a portion of at least one of the plurality of reed switches within the support board. In one version of this embodiment, a plurality of elongate recesses in the support board, each elongate recess configured for receiving at least a portion of one of the reed switches within the support board below a switch-side surface of the board. In an enhancement, each of the elongate recesses is established by an aperture extending through the support board where the aperture receives a bottom portion of the reed switch thereby minimizing a distance between a longitudinal axis of the reed switch and a widthwise axis of the support board.
In one embodiment, the support board is sufficiently flexible to be bent into an arc along the board""s lengthwise axis and so that the arc has a radius at least as short as one and one-half feet thereby accommodating a coiled configuration of the detection unit.
In still another embodiment, the support board is a printed computer circuit board and the elongate recesses in the circuit board have longitudinal axes oriented substantially perpendicular to the board""s longitudinal axis thereby configuring the board for automated installation of the plurality of reed switches thereupon.
The detection unit has a plug end and an opposite plug receiving end for interconnecting a plurality of detection units into an end-to-end plugged series so that the series is capable of variable length which is determined by the number of detection units plugged together.
Each detection unit has a reporting and repeating module interconnected therewith for detecting closed reed switches actuated by the magnet and reporting the closed switch condition to a controlling interface for a plurality of the modules. Each of the reporting and repeating modules being capable of communication exclusively with adjacent modules in the plugged series thereby requiring information communicated along the series of detection units to be relayed through each interposed module that receives the information and repeats the information to a next module in the series.
Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.
The beneficial effects described above apply generally to each of the exemplary devices and mechanisms disclosed herein of the relative location detection sensor. The specific structures through which these benefits are delivered will be described in detail hereinbelow.